Chinese Calendar

This page describes how the Chinese lunar calendar system works (this page). Elsewhere in our calendar section we have a display of the Chinese calendar for the current month (or any other month 2010-2020) as well as a whole year calendar for 2018 and 2019.

It has always been vital to know the accurate date in the year so things are done at the correct time. Many activities are keyed to the calendar: when seeds must be planted; grain harvested; fruit gathered and sheep moved to upland. So from the earliest times it has been essential to correctly track the passage of the year.

The Sun

Frogs and toads are valued in China because they keep down insect pests on crops. In some regions their name is similar to qián 'money, coin' and this has given them an assoication with good fortune and luck.

The earth goes around the sun once every 365.2425 days. This number is rather inconvenient as it can not be divided up into a whole number of days. To work out the day within the year you can measure the angle of the sun at midday, but this assumes you have an accurate idea of time. It is at its highest at the Summer Solstice ➚ on21st/22nd June and lowest Winter Solstice 21st/22nd December [Northern hemisphere]. If you have some sort of clock you can measure when the length of a day is equal to the length of a night, and so identify the Spring and Autumn Equinoxes ➚. The earliest astronomical instrument is just a stick in the ground - a gnomon ➚ to measure the sun's shadow - from which the sundial is a direct descendent.

To keep the solar calendar in synchronization with the earth’s orbit in the Julian Calendar ➚ an extra leap day needs to be inserted into the calendar every four years (4 x 0.25 = 1). However, the number of days is actually a little less than 365.25 it is closer to 365.2425, to account for this discrepancy the Gregorian calendar ➚ was devised with additional rules for leap days in century years (1900 was not a leap year but 2000 was). By the time the Gregorian system was introduced in 1582, the old Julian calculation had drifted from the true solar time by ten days or more. The Orthodox Eastern Church ➚ has still not accepted the Gregorian system and that is why they celebrate Easter ➚ on a different date.

The Stars

Perhaps more useful than using the sun as a clock is to take a look up at the stars. [For more on Chinese constellations please visit: Chinese stars and constellations]. The sun appears to move relative to the backdrop of stars in an annual cycle - and so the constellation the sun is currently in front of tells you the approximate date. As the sun is so bright, this observation has to be made just before sunrise or after sunset. The Chinese used the pole star and circumpolar stars rather than the sun as these are easier to observe accurately. As summer progresses different stars and constellations appear above the southern horizon ➚ and this is another way of working out the date.

The Moon

The moon has been the most useful clock for thousands of years. The moon takes 29.53 days to go around the earth and just as importantly the phase of the moon changes through this period from full to half to new to half and back to full again. By carefully tracking the phase of the moon you can work out the day within a month. It is best to work with the new moon as the starting day of the month, as it is easy to see when the disc is entirely dark without even a slither of light at its edge. People can then easily count through the days within the month up to 29, so as long as it is agreed when is the day of the new moon, you can agree dates and make arrangements for particular future days.

The word ‘calendar’ comes from the Latin kalendae ➚ ‘to announce’ referring to the Roman custom of announcing the official new moon that started the month. Everyone could then start counting the days within the new month.

Most regrettably the date calculated by the sun is out of step to that by the moon. There are 12.37 lunar orbits in a year and coping with this awkward number was a real problem for ancient civilizations. If this was a whole number then calendars would be far simpler. It is likely that this incomplete thirteenth month of the solar year is the origin of 'unlucky thirteen'.

One coincidence is that 19 x 12.37 is very close to the whole number of 235 and so the lunar and solar cycles roughly repeat each other every 19 years - this is the Metonic cycle named after the Greek mathematician Meton ➚, who discovered it in 432BCE.

Chinese Calendars

China has adopted the Western, Gregorian system of oddly formed months with extra leap days at the end of February to correct for the true length of solar year. This was introduced into China when it became a Republic in 1912. New public holidays such as Labor Day (May 1st) and National Day (October 1st) are fixed on the Gregorian calendar.

China developed its traditional calendar system independently from the West. China has two calendars which are still followed today, one based on the moon and one on the sun.

The lunar Chinese calendar is the most important as it determines the dates of many Chinese traditional festivals. Instead of adding in an extra leap day every four years the calendar introduces a whole leap month every couple of years. The calendar follows the moon precisely so months are either 29 or 30 days long according to accurate predictions of the occurrence of the new moon at a specific place. The months are called 小月xiǎo yuè small months (29) and 大月dà yuè big months (30) and are numbered rather than named.

Once you know the numbers 1 to 12 it is easy to understand the date and time in Chinese.

This may seem a little complicated until you bear in mind that some Christian festivals such as Easter are still synchronized to the moon and not the sun. Christians had to develop similarly complex calculations to work out the date for Easter ➚ each year.

Seasons

The start of the Chinese lunar year 年nián is at the Spring Festival or Chinese New Year, timed as the second new moon after the Winter Solstice.
The Chinese originally split the year into two seasonsSpring春chūnand Autumn秋qiū (hence the name 'Spring and Autumn period'). These were split to form the four modern seasons by adding Summer夏xià and Winter冬dōng . The lunar months were named within the season so 孟春mèng chūn was the first month of Spring; 中春zhōng chūn the second month and 季春jì chūn the last month of Spring.

Intercalary months

The position in the year that the Chinese leap (intercalary) month is added varies from year to year. In 2012 it was added after the fourth month and in 2014 after the ninth month. The month is called after the normal month it follows with the addition of ‘leap’闰rùn month. So the sequence in 2012 was 四月sì yuè followed by 四闰月sì rùn yuè. A year with a leap or double 8th month is considered an unlucky year (1976, 1995, 2014 and 2033). The addition of the extra month gives a length of year that varies between 353 to 385 days.

The invention of the lunar calendar is attributed to the Yellow Emperor back in the mists of ancient China. Very accurate astronomical measurements need to be taken to keep the lunar calendar in step with the complex orbit of the moon. For many centuries the Purple Mountain Astronomical Institute ➚ at Nanjing calculated the calendar for China.

Weeks

There is no astronomical basis for a seven day division of the year, unless perhaps, as roughly one quarter phase of the moon. The Chinese originally had a ten day week 旬xún as this divides a month nearly precisely into three (four seven day weeks gives 28 days while three ten day weeks gives 30 days while the accurate month length is 29.53 days). At this time the days of the week were named after the Ten Heavenly Stems ➚ (tian gan).

The traditional Chinese calendar is still used to determine the date of some festivals, and in particular the most important one - Chinese New Year. Our calendar shows each month with both Chinese and Western calendar information together with all the important anniversaries occurring on each day and the whole year.

Lunar dates

You will see some extra characters on Chinese calendars (including our own free calendar) :
The day of the lunar month in the range 1 to 9 uses the character prefix 初chū for ‘early’. Instead of using three characters for 21 to 29 (二十一èr shí yī etc.) a special character for ‘twenty’ 廿niàn is used. Similarly the number 31 is sometimes represented by ‘thirty’ 卅sà. This convention gives all days a convenient two character form.

Lunar names

The months 2 to 10 are now numbered as you would expect but there is the special case of the first month which is called (正zhēng).
To keep to the same two character format as with days, the 11th month is sometimes called 冬dōng (cold) and the 12th month is 腊là (an alternative meaning is dried meat reflecting the lack of fresh meat in January).

Although lunar months are normally numbered they also have traditional poetic names.

The traditional Chinese calendar is still used to determine the date of some festivals, and in particular the most important one - Chinese New Year. Our calendar shows each month with both Chinese and Western calendar information together with all the important anniversaries occurring on each day and the whole year.

The Lichun solar calendar

If you are a farmer it is the sun not the moon that determines when seed needs to be planted, corn harvested, and lambs are due to be born. The Chinese Lunar calendar may be out by over ten days compared to the sun, and this length of time in a short growing season is important. So the alternative ‘agricultural’ or 岁suì calendar is based on the sun. It has its origin in farming and it is still noted in Chinese calendars and almanacs. Two important traditional festivals are fixed according to the sui calendar: the Qing Ming festival and the Dongzhi (Mid Winter) festival.

The sui calendar uses 24 intervals of 15 or 16 days and, because they are based on the sun, fall on approximately the same Gregorian calendar date each year (plus or minus a day). These are called 节气jié qì and date back to the Zhou dynasty,
The table below gives the jieqi name and the days according to the Gregorian calendar, if one day is more likely than another that day is given first.

To master both solar and lunar calendars, Almanacs ➚ are widely published with guides to the best days of the year for doing all sorts of things, from felling trees to drying clothes and getting married.

Years

Years are now counted just like ordinary numbers; the year of the Common Era. In Imperial China years were specified as the number of years of Emperor’s reign or, after 1911, from Yellow Emperor Huangdi's birth. This scheme was also used in Europe in medieval times. By tradition a life span was at most 60 years, and so a special sexagesimal year numbering system was also used for the Chinese astrological year. There is some evidence that in ancient days people who reached the age of sixty were buried alive in northern China as it was considered unnatural to live longer than that. The first years of the new cycle were considered the appropriate time to launch a revolution. Emperor Qianlong abdicated his rule after sixty years of reign in 1794 as he stated in his abdication proclamation that his cycle of rule had ended.

The sixty year cycle, used since the Han dynasty, is made up of the Ten Heavenly Stems (天干tiān gàn) combined with Twelve Earthly Branches (地支dì zhī) that are also used for the astrological years.

The 12 year cycle of branches has its origin as far back as the Shang dynasty in the orbit of the planet of Jupiter. Early observations had shown Jupiter takes about 12 years to orbit the sun (11.86 is the actual figure), and the twelve branches was used to denote the years in the cycle. The earthly branches also denote a direction (see our astrology page) so compasses had 12 divisions not 4 or 8 as in early Western systems.

In ancient times the Chinese split the year into six 60 day periods (double months) to make a 360 day year and so the historic importance of cycles of 60 can be clearly seen. It is interesting that the Mesopotamians ➚ used units of sixty for everything, from which we have ended up with 60 minute hours and 60 second minutes. In China there is a traditional epoch of 60x60x60x16x7 years making up 24,192,000 years.

The Ten Heavenly Stems 十天干shítiāngān

The heavenly stems are associated with a number, an element and a particular associations.
Their principle use as 'ordinals' from ancient time so the third day or the third year would both use the ordinal stem character 丙bǐng. A week in Shang dynasty times (as recorded on oracle bones) was ten days long. Some legal documents today still use these characters for numbering.

Sexagesimal Cycles干支gānzhī

They are incremented in step to form a cycle of 60 so that:

1 : 甲子 1st stem and 1st branch is followed by 2: 乙丑 2nd stem and 2nd branch then 3: 丙寅 3rd stem and branch and so on up to 10: 癸酉 having run out of stems for 11 the stems start again at one but the stems continue at 11: 甲戌; 12: 乙亥, now at 13 the cycle of branches starts again 13:丙寅. The sequence does not repeat until 60 :癸亥guǐhài. It may seem a cumbersome system, but it is less prone to misreading or mishearing as two characters together provide the number not just one. To record a year these two characters were combined with the Emperor's reign name. Here is the complete table of the 60 year names of the Sexagesimal Cycle.

The cycle of sixty was all important for recording times as it was not only used for counting the years but also day within the year and time of day. Four ganzhi together give the exact time: year, month, day, time of day.

1 甲子jiǎ zǐ

13 丙子bǐng zǐ

25 戊子wù zǐ

37 庚子gēng zǐ

49 壬子rén zǐ

2 乙丑yǐ chǒu

14 丁丑dīng chǒu

26 己丑jǐ chǒu

38 辛丑xīn chǒu

50 癸丑guǐ chǒu

3 丙寅bǐng yín

15 戊寅wù yín

27 庚寅gēng yín

39 壬寅rén yín

51 甲寅jiǎ yín

4 丁卯dīng mǎo

16 己卯jǐ mǎo

28 辛卯xīn mǎo

40 癸卯guǐ mǎo

52 乙卯yǐ mǎo

5 戊辰wù chén

17 庚辰gēng chén

29 壬辰rén chén

41 甲辰jiǎ chén

53 丙辰bǐng chén

6 己巳jǐ sì

18 辛巳xīn sì

30 癸巳guǐ sì

42 乙巳yǐ sì

54 丁巳dīng sì

7 庚午gēng wǔ

19 壬午rén wǔ

31 甲午jiǎ wǔ

43 丙午bǐng wǔ

55 戊午wù wǔ

8 辛未xīn wèi

20 癸未guǐ wèi

32 乙未yǐ wèi

44 丁未dīng wèi

56 己未jǐ wèi

9 壬申rén shēn

21 甲申jiǎ shēn

33 丙申bǐng shēn

45 戊申wù shēn

57 庚申gēng shēn

10 癸酉guǐ yǒu

22 乙酉yǐ yǒu

34 丁酉dīng yǒu

46 己酉jǐ yǒu

58 辛酉xīn yǒu

11 甲戌jiǎ xū

23 丙戌bǐng xū

35 戊戌wù xū

47 庚戌gēng xū

59 壬戌rén xū

12 乙亥yǐ hài

24 丁亥dīng hài

36 己亥jǐ hài

48 辛亥xīn hài

60 癸亥guǐ hài

At the turn of the 20th century the birth of a Republic removed the numbering of years of the reign of the Emperor. They chose to adopt the traditional count of years since the birth of the Yellow Emperor Huangdi. It is based on the 'lunar' year so the year number advances on the day of the Chinese New Year (Spring) festival. So January 28th 2017 was the start of Chinese year 4715. Sometimes the sexagesimal year is noted relative to this base year so 2018 is the 35th year of the 78th cycle since Huangdi. To find the Chinese year add 2698 to the Christian year, but take one off if the date precedes the Chinese New Year (Spring Festival).

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